My friend is going to meet rabbi, to talk about house management, and she wants to bring some present to him. What you would present to the rabbi, and what you should not to? Please explain why.
There is no need to bring a present in the first place, but it is a kind gesture. Rabbis are paid to serve their congregants and community for a variety of reasons relating to philosophy, halacha, et cetera.
If you could give a price range, this question can be better answered; however, I'll just throw a general answer out in the open. You can always buy the rav a bottle of wine. I recommend a kosher merlot. The merlot hyperlinked is pretty nice, sold at a reasonable price, and serves as a nice gift. I answer wine because it's so versatile. The rabbi can use it for kiddush at the shul, open it up with his family during Shabbos dinner, or simply use it for havdalah and officially end Shabbat with a nice taste.